HCPCS Code A4639: Replacement pad for infrared heating pad system

Key Takeaways

HCPCS Code A4639 describes a replacement pad for an infrared heating pad system, classified as a Level II HCPCS supply code in the A-series.

Medicare Part B does not cover A4639, or its parent device E0221 – CMS National Coverage Determination (NCD) 270.6 nationally excludes infrared heating pad systems and their accessories as not reasonable and necessary.

Because denial is automatic and expected, suppliers should issue an Advance Beneficiary Notice (ABN) before delivery and apply the correct modifier (GA, GZ, or GY) to shift financial liability to the beneficiary rather than absorbing the cost.

Practice management software like Pabau helps DME suppliers and practices track ABNs, modifier selection, and delivery documentation, reducing billing disputes before they start.

HCPCS Code A4639 is the Level II HCPCS supply code for a replacement pad for an infrared heating pad system. Medicare Part B does not cover it.

The Centers for Medicare and Medicaid Services (CMS) designated infrared heating pad systems and their accessories as not reasonable and necessary under National Coverage Determination (NCD) 270.6, so claims are denied regardless of documentation.

Suppliers who issue an Advance Beneficiary Notice (ABN) and apply the correct modifier before delivery shift that cost to the beneficiary instead of absorbing it themselves.

The code sits within the A4000-A4999 series of the HCPCS Level II codes, which CMS maintains and updates annually for medical and surgical supplies billed outside physician services. It has been active since approximately 2000 and carries no current termination date.

The A-code series covers consumable and replacement supplies furnished to Medicare beneficiaries. A4639 is specifically a replacement supply code, meaning it applies when the original pad wears out or requires replacement, not to the initial device purchase. Billers sometimes confuse this with the parent device code – the distinction matters for claim submission.

Infrared heating pads are commonly used in physical therapy and sports medicine settings for pain management, which is where DME suppliers most often bill A4639.

Medicare coverage and eligibility for HCPCS Code A4639

Medicare Part B does not cover HCPCS Code A4639, and it does not cover the parent device either (E0221, infrared heating pad system). Under NCD 270.6, effective October 24, 2006, CMS determined that infrared heating pad systems and their accessories – including replacement pads – are not reasonable and necessary.

This is a blanket national non-coverage policy, not a documentation-contingent conditional coverage rule. No amount of physician ordering or medical necessity paperwork unlocks payment.

The companion CMS Policy Article A52477 states that NCD 270.6 “precludes payment for these items,” and the related LCD L33825 confirms the device and its accessories “will be denied as not medically reasonable and necessary.”

Suppliers who bill Medicare directly for A4639 without an Advance Beneficiary Notice (ABN) on file risk absorbing the cost themselves, since an automatic denial without a signed ABN generally means the supplier, not the beneficiary, is liable.

The claims management workflow for A4639 should be built around ABN issuance and modifier selection, not around proving medical necessity.

What NCD 270.6 means for suppliers

• Medicare will deny every A4639 claim, and every E0221 claim, regardless of documentation, physician order, or medical necessity evidence
• The exclusion applies nationally – it is not subject to MAC-level discretion or appeal on medical necessity grounds
• A signed Advance Beneficiary Notice (ABN) is the mechanism that allows a supplier to bill the beneficiary directly for the item
• Commercial and other non-Medicare payers set their own coverage policy for infrared therapy devices – many also treat these as non-covered or investigational, so verify separately before billing

ABN and modifier requirements

Because denial is automatic and expected, suppliers should issue an ABN before delivering the replacement pad and select the modifier that matches what happened with the ABN when (and if) a claim is submitted to Medicare:

• Modifier GA: a valid ABN was signed by the beneficiary before delivery – use this to shift financial liability to the beneficiary
• Modifier GZ: no ABN was obtained – the claim is expected to be denied and the supplier cannot bill the beneficiary for the denied amount
• Modifier GY: used when the item is treated as statutorily excluded from the Medicare benefit – some MACs expect this designation for infrared therapy accessories instead of GA/GZ – confirm with your DMEPOS MAC which one it expects

Keeping a signed ABN, the delivery record, and (if a claim was submitted) the Medicare denial notice in the patient file protects the supplier’s ability to collect from the beneficiary and supports any billing dispute.

Practices managing DMEPOS billing alongside clinical workflows benefit from structured digital documentation processes that keep signed ABNs, delivery records, and denial notices attached to the patient record and ready to produce if a beneficiary disputes a charge.

2026 Fee schedule and payment rates for A4639

CMS still publishes an annual DMEPOS fee schedule amount for A4639, but a published rate does not mean Medicare will pay it. Because infrared heating pad systems and their accessories are nationally non-covered under NCD 270.6, Medicare will not reimburse A4639, or E0221, at any rate, in any locality.

The fee schedule figure below matters mainly as a reference point for what a supplier may charge a beneficiary directly under a signed ABN, or for billing non-Medicare payers who may cover the item under their own policy. Always check the official CMS HCPCS fee schedule files for the current published figure.

Important: A dollar figure exists in the CMS fee schedule files and changes with each annual update, but that number is not what Medicare will pay for A4639. National non-coverage under NCD 270.6 blocks payment outright.

Use the PGM Billing HCPCS lookup tool or the official CMS DMEPOS fee schedule download only as a reference for ABN-based beneficiary billing or non-Medicare payer submissions, not as an expected Medicare reimbursement.

How to bill HCPCS Code A4639

Billing A4639 under Medicare Part B is shaped entirely by its national non-coverage status. The goal is managing beneficiary liability correctly through an ABN and the right modifier, not securing payment.

The steps below apply to DME suppliers billing via their DMEPOS MAC. Practices billing on behalf of a supplier should confirm jurisdiction assignment before any claim submission.

1. Confirm the non-coverage applies. Before delivering the replacement pad, confirm the item falls under NCD 270.6 (infrared heating pad systems, HCPCS E0221, and accessories including A4639). Medicare will not pay regardless of documentation.
2. Issue an Advance Beneficiary Notice (ABN). Provide the beneficiary a properly completed ABN before delivering the pad, explaining that Medicare is expected to deny the claim and that they will be responsible for payment.
3. Decide whether to submit a claim to Medicare. Suppliers may submit a claim purely to generate a formal denial (useful for secondary insurance or the beneficiary’s records), or may bill the beneficiary directly without submitting to Medicare at all, per the beneficiary’s ABN election.
4. Select the correct claim form. DMEPOS suppliers use the CMS-1500 claim form (or its electronic equivalent, the 837P transaction) if submitting to Medicare for a denial.
5. Apply the correct modifier. Use GA if a valid ABN was signed before delivery, GZ if no ABN was obtained, or GY if the item is treated as statutorily excluded – confirm with your DMEPOS MAC which designation it expects for infrared therapy accessories.
6. Submit to the correct DMEPOS MAC. A4639 claims route to either Noridian (Jurisdictions A and D) or CGS Administrators (Jurisdictions B and C) depending on the beneficiary’s state of residence. Confirm jurisdiction assignment before submission.
7. Bill the beneficiary directly. Once the Medicare denial is received (or immediately, if bypassing Medicare submission per the ABN), invoice the beneficiary for the full charge as disclosed on the ABN.
8. Retain all documentation. Keep the signed ABN, delivery confirmation, and any Medicare denial notice for a minimum of seven years – this is the documentation that supports the supplier’s right to bill the beneficiary and what auditors request first.

DMEPOS MAC jurisdiction reference

HCPCS Code A4639 claims are processed by one of two DMEPOS MACs depending on the beneficiary’s state. Submitting to the wrong MAC causes automatic rejection.

Practices managing complex billing workflows across multiple DMEPOS codes benefit from integrated EHR systems that surface jurisdiction-specific rules automatically rather than requiring staff to check MAC websites before each submission.

Related HCPCS codes and code crosswalk

Selecting the wrong code is the second most common billing error on infrared heating pad claims. The table below maps A4639 to adjacent codes in the same device and supply category, with guidance on when each applies. Practices managing DME billing should review this crosswalk as part of routine compliance review processes.

DME suppliers processing A4639 replacement claims often bill related supply codes in the same window, including A4626 and A4614.

Suppliers managing broader DME equipment lines also bill adjacent codes like E0260 within the same claims cycle.

Key distinction: E0221 is the infrared heating pad system itself, and A4639 is the replacement pad for that system. Bill E0221 when the device is first provided, and bill A4639 for subsequent replacement pads.

Both codes are nationally non-covered by Medicare under NCD 270.6, so correct code selection affects claim accuracy and ABN/modifier handling, not eligibility for payment. Medicare will not pay either code, and billing A4639 for the initial device supply is still a coding error that can trigger a rejection and a compliance flag independent of the coverage issue.

Suppliers who also bill CPT codes for therapy modalities alongside DME supplies should confirm documentation requirements in physical therapy billing, since payer rules can differ between DME and therapy claims.

Manage DME billing documentation in one place

Pabau helps practice teams keep ABNs, delivery records, and denial documentation organized and audit-ready. Clear liability documentation means fewer billing disputes and faster beneficiary collections.

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Common billing errors and compliance tips

Because A4639 is nationally non-covered, the compliance risk here is mishandling the ABN, modifier, and beneficiary-billing steps that follow the denial, not the denial itself. The errors below are the most frequent causes of billing disputes and audit findings on A4639 claims.

Error 1: Billing Medicare and expecting payment

Some billers still treat A4639 as a conditionally covered supply code and submit claims expecting reimbursement once documentation is complete. NCD 270.6 makes this impossible: Medicare denies every A4639, and every E0221, claim regardless of documentation.

Build the expectation of automatic denial into your workflow from the start, and use any claim submission to generate a formal denial rather than to seek payment.

Error 2: Submitting without the correct modifier

Claims for A4639 submitted without modifier GA, GZ, or GY are frequently returned as unprocessable rather than denied outright, which delays the paper trail a supplier needs to bill the beneficiary.

Confirm with your DMEPOS MAC which modifier it expects for infrared therapy accessories, and apply it on every claim submitted for denial purposes. Modifier requirements can differ between Noridian and CGS, so apply the correct MAC’s rules based on beneficiary jurisdiction.

Error 3: Using E1399 instead of A4639

When billers cannot quickly locate the correct code, they sometimes default to E1399 (DME miscellaneous). E1399 requires manual review by the MAC and often results in denial or significant payment delay.

A4639 is the specific code for this supply, and a specific code always takes precedence over a miscellaneous fallback. Refer to the AAPC HCPCS code lookup to confirm the correct code before defaulting to a miscellaneous option.

Error 4: Submitting to the wrong DMEPOS MAC

A4639 claims must be submitted to the DMEPOS MAC that covers the beneficiary’s state of residence, not the supplier’s state. A biller located in Texas submitting a claim for a beneficiary in New York must submit to Noridian, not CGS.

Routing the claim to the wrong MAC causes an immediate rejection and resets the timely filing clock. Verify jurisdiction for every new beneficiary and after any reported address change.

Error 5: No ABN issued before delivery

Delivering the replacement pad without a signed ABN forfeits the supplier’s ability to bill the beneficiary once Medicare denies the claim, or would deny it if one were submitted. The cost falls on the supplier instead.

Issue the ABN before delivery every time, for both the parent device and any replacement pad, and keep a signed copy in the beneficiary’s file.

Practices that manage DME billing as part of a broader patient care workflow can reduce these errors significantly with automated billing workflows that flag incomplete documentation before a claim is submitted rather than after it is denied.

Conclusion

A4639 looks like a routine DMEPOS supply code, but it carries an important exception. Medicare has nationally excluded infrared heating pad systems and their accessories from coverage under NCD 270.6, and no amount of physician ordering, medical necessity documentation, or replacement-interval tracking changes that outcome.

What matters here is making sure an ABN is signed before delivery, the right modifier is applied if a claim is submitted, and the beneficiary is billed correctly once Medicare’s denial is confirmed.

Pabau’s claims management software gives practice teams a structured way to track ABNs, modifier selection, and delivery documentation so nothing falls through the cracks between an expected denial and beneficiary billing.

If your practice manages DMEPOS billing alongside clinical operations, book a demo to see how Pabau handles the documentation and workflow side of supply code billing.

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